TECHNICAL FIELD

The present disclosure relates to a valve assembly for jetting of a viscous media in a media jetting device for controlled media jetting in manufacturing of three-dimensional products, such as in a 3D printing device for manufacturing of one or more 3D products by additive manufacturing. The disclosure also relates to an array of such valve assemblies, to a method of controlling such a valve assembly, to a 3D printing device and to a use of a valve assembly.

BACKGROUND

Additive manufacturing techniques comprise a process involving forming or combining materials in order to manufacture 3D products from 3D modeling data, typically from a computer-assisted design file.

A number of additive manufacturing techniques have been developed.

For example, in Fused Filament Fabrication (FFF) technology (including Fused Deposition Modeling FDM), a continuous filament of thermoplastic material is extruded and hardened or cured to a 3D product. Typical filament materials include ABS, PLA, IPS, TPY and nylon.

Stereolithography (SLA) involves layer-by-layer deposition of material, using photochemical processes for the material to cure.

Selective laser sintering (SLS) and selective laser melting (SLM) are examples of additive manufacturing techniques where a matrix material is supplied in the form of a powder, for example plastic, metal, ceramic or glass. In SLS, a laser is used as a power source to selectively sinter the powdered material, whereas in SLS, a laser is used as a power source to selectively melt the powdered material, so as to form a mass with the desired 3D shape. Another additive manufacturing technique is known as binder jetting (BJ). Binder jetting utilize powders which are bound together with liquid binder agents working as adhesives to form the desired 3D shapes. Typically, the powder material may be a metal powder, in which case the binder material may be removed from the matrix created during additive manufacturing by application of heat, and optionally replaced e.g. by pouring metal into the voids left in the matrix from the removed binder material so as to produce an all-metal 3D part. Optionally, the powder material may instead be a sand powder, in which case no post-processing generally takes place, but the final 3D part is formed by the sand powder and the cured binder.

Another option for material powder in binder jetting is a wood powder. With wood powder as a matrix material, no post-processing generally takes place, but the final 3D part is formed by of the wood powder and the cured, solidified or dried binder. The binder material may be a water-based adhesive, a thermoplastic adhesive or a two-component adhesive, such as acrylate, epoxy or polyester based adhesives.

To perform the additive manufacturing techniques mentioned in the above, there is a need to eject materials in viscous form with high accuracy and at very high speed. To this end, various valves for jetting viscous material have been developed.

Valves for 3D manufacturing must be able to create a material jet for printing at very precise intervals, meaning that the valves should be able to be controlled to completely open/close within a time period in the range of 2 ms or less.

Further, when a high level of geometrical accuracy is required, it may be desired that the dimensions of the valves are limited, e.g having an outer width being less than 10 mm. In use, a plurality of valves may be assembled to form a valve array. Such a valve array would typically comprise 32 to 128 valves. The valves in an array may be individually controlled for precise 3D manufacturing.

Depending on the material to be ejected, various additional demands may be put on the valves. The valves may be adapted for ejection of a material which is per se ready to form a product, for example a plastic material in melted form in the case of FFF or FDM fabrication.

However, the valves may also be adapted for ejection of a binder material which is to be combined with a matrix material, e.g. powder material as in the binder jetting methods described in the above.

As mentioned in the above, it may be desired to be able to eject binder material being a two-component binder, such as acrylate, epoxy or polyester based adhesives. This type of binder materials comprise binder materials which are generally highly reactive and may pose particular demands on the valves.

Initially, many two-component binders exhibit a relatively high viscosity, for example in the range of 50 to 10000 mPas. This implies that the valve should be able to eject fluid materials set at a high pressure, e.g. more than 200 bar, but preferably at least 15 to 60 bar. Notably, this puts a demand on the valve to be able to close without leakage at high pressures.

Moreover, many two-component binders have highly corrosive properties, which restricts the possibility of freely selecting materials for the valve.

Some two-component binders are also sensitive to friction, in that when subject to the shearing which may appear in a working valve, the binders are prone to shifting form from fluid to crystal. The crystals formed in the binder may be highly abrasive, further increasing friction and wear, which in turn may shorten the lifespan of the valves.

It is generally desired that the valves are durable and wear resistant such that they are able to sustain a large number of openings/closings before becoming worn out or require regeneration. For example, it may be desired that the valve shall sustain ³ 30 million cycles of opening/closing.

If the binder accidentally cures in the valve, it is desired that the valve can be cleaned and/or regenerated. A cleaning procedure as such may require e.g. pyrolytic cleaning. In view of the above-mentioned demands for a valve for 3D manufacturing, in particular for a valve suitable for use in valve assemblies for extruding a high-viscosity binder such as for example a two component adhesive, there is a need for improvement in relation to one or more of said demands.

Further, such a valve may be advantageous in general where controlled media jetting is required, in particular for controlled jetting of viscous media, and in particular of viscous media which puts particular demands on the valve.

SUMMARY

A valve assembly fulfilling one or more of the above-mentioned needs is provided by a valve assembly according to claim 1. Further variants or aspects fulfilling one or more of the above-mentioned needs are provided by the enclosed independent and dependent claims.

As such, there is provided valve assembly for jetting of a viscous media in a media jetting device for controlled media jetting in manufacturing of three-dimensional products, such as in a 3D printing device for manufacturing of one or more three-dimensional products by additive manufacturing. The valve assembly comprises a valve compartment, said valve compartment comprising at least a media chamber portion, wherein the valve assembly is configured for ejection of said viscous media via said media chamber portion; and a valve member being configured to assume a closed position hindering said pressurised media from being ejected via said media chamber portion and an open position allowing said pressurised media to be ejected via said media chamber portion.

Said valve member comprises a valve stem arranged to extend into said media chamber portion and said valve stem being movable in relation to said media chamber portion to enable said valve member to assume said closed position and said open position, and configured to be operatively connected to an actuator for controlling said movement of the valve member. The valve member further comprises a resilient membrane, said resilient membrane being fixedly connected to said valve stem.

The resilient membrane is arranged to provide a seal between said valve stem and said media chamber portion during said movement of said valve stem in relation to said media chamber portion, by at least a sealing portion of said membrane sealing towards a membrane seat, said membrane seat being provided at a fixed location in relation to said media chamber portion, and a first side of said membrane is subject to a media pressure residing in said media chamber portion, and, said valve assembly being configured for applying a pressurised fluid to a second side of said membrane opposing said first side.

The valve assemblies as disclosed herein are preferably high-precision valves having short opening/closing times, preferably in the order of 3 ms or less, e.g. 2 ms or less, as well as a long service life, the valves preferably being configured to sustain ³ 30 million cycles of opening/closing.

The resilient membrane is fixedly connected to the valve stem, and at least a sealing portion of said membrane is arranged to provide a seal between the valve stem and the media chamber portion at a fixed location in relation to said media chamber portion, while the valve stem is movable in relation to said media chamber portion. Accordingly, there will be substantially no frictional forces between the valve stem and the resilient membrane, or between the resilient membrane and the media chamber portion during the movement of the valve stem.

Due to the resilience of the membrane, the sealing portion of the membrane may remain in sealing contact at said fixed location to the media chamber portion, while another portion of the membrane, being fixedly connected to the valve stem, is movable together with the valve stem.

The valve stem is configured to be operatively connected to an actuator for controlling the movement of the valve member for opening and closing the media outlet of the valve assembly. Accordingly, the valve stem is arranged in relation to the actuator such that the movement of the valve stem may be controlled by the actuator. The actuator may be arranged so as to directly or indirectly act upon the valve stem.

The resilient membrane may be arranged at various locations in relation to the valve stem.

For example, a first portion of the valve stem may be configured to be operatively connected to an actuator for controlling the movement of the valve member for opening and closing the media outlet of the valve assembly, and a second portion of the valve stem may be configured to enable said valve member to assume said closed position and said open position. Optionally, resilient membrane may be fixed to the valve stem at a location between said first and second portions of the valve stem. In another option, the resilient membrane may be fixed to the valve stem at a location corresponding to said first portion.

The valve stem may be formed by one or several parts. The resilient membrane may for example be formed by a part which also forms a portion of the valve stem, e.g. a part with a central portion which will form a portion of the valve stem, and a radially extending portion which forms the resilient membrane.

Because of the media pressure which resides in the media chamber when the valve assembly is in use, the actuator need only to be arranged to urge the valve stem towards a direction counteracting said media pressure.

It will be understood that the parts forming e.g. the valve stem or the valve member may be interconnected or they may be separate, adjacent parts, as long as they perform the function of transferring forces between the actuator and the media pressure in the media pressure chamber.

The actuator may be arranged to act directly on the valve stem or indirectly on the valve stem, for example via another portion of the valve member, or via a separate transfer part.

The actuator may for example be an air pressure actuator supplying air pressure for controlling the movement of the valve member.

In this context, it may be mentioned that the pressurized fluid applied to the second side of said membrane is not forming the actuator for controlling the movement of the valve member or of the valve stem. The control of the pressure of the pressurized fluid applied to the second side of said membrane is different from the control of the actuator for controlling the movement of the valve member, i.e. the opening and closing of the valve. The pressurised fluid is applied to the second side of the membrane to counteract the media pressure on the first side of the membrane, enabling the membrane to perform its sealing function while diminishing attrition and risk of breaking. A further advantage with the valve assemblies as disclosed herein is that they may be adapted to be controlled so as to jet viscous media in brief intervals, creating dots or droplets of the ejected viscous media, or in longer intervals, creating continuous strings of the ejected viscous media. Hence the valve assemblies allows for controllable selection of the opening time of the valve, increasing versatility during manufacture of three- dimensional products.

Optionally, the membrane forms a membrane disc surface forming said sealing portion of said membrane, preferably said membrane disc surface extends radially from and circumferentially about said valve stem. The disc surface hence extends from the valve stem to an outer perimeter of the membrane. For example, an inner portion of such a membrane disc surface may be fixedly connected to the valve stem, whereas an outer portion of said disc surface may form said sealing portion. Said sealing portion of said membrane may preferably form a closed perimeter about said valve stem.

Preferably, the membrane may be generally circular, although other geometrical shapes might be possible.

Optionally, said media chamber portion is having a media inlet for receiving pressurised viscous media, and a media outlet for ejection of said viscous media.

Optionally, said valve stem is configured to be movable along a valve axis (X) in a closing direction to said closed position, and in an opening direction to said open position.

Optionally, in said closed position, said valve member is in a position closing said media outlet, and in said open position, said valve member is in a position removed from said media outlet, allowing said pressurised media to be ejected through said media outlet.

Optionally, said valve stem extends generally along said valve axis X.

Optionally, said sealing portion of said membrane faces a direction parallel to said valve axis X. With “facing a direction parallel to said valve axis” is meant herein that a normal to an outer surface of said sealing portion, when divided into one component parallel to said valve axis and one component perpendicular to said valve axis, displays at least a non zero component parallel to said valve axis. Optionally, said sealing portion of said membrane mainly faces a direction parallel to said valve axis X. With “mainly faces a direction parallel to said valve axis” is meant herein that a normal to an outer surface of said sealing portion, when divided into one component parallel to said valve axis and one component perpendicular to said valve axis, the component parallel to said valve axis is greater than the component perpendicular to said valve axis.

Optionally, said sealing portion of said membrane may be generally perpendicular to said valve axis X, i.e. a normal to the sealing portion extends generally parallel to said valve axis X.

It is to be understood, that the location of the sealing portion in relation to the valve axis X as discussed in the above is to be considered in a position wherein the sealing portion forms said seal between the valve member and the media chamber portion.

Optionally, said media chamber portion comprises said membrane seat, and said sealing portion of said membrane is arranged to provide said seal between said valve stem and said media chamber portion at said membrane seat, providing said fixed location in relation to said media chamber portion.

Optionally, said membrane seat faces a direction parallel to said valve axis X. Wth “facing a direction parallel to said valve axis” is meant herein that a normal to an outer surface of said membrane seat, when divided into one component parallel to said valve axis and one component perpendicular to said valve axis, displays at least a non-zero component parallel to said valve axis.

Optionally, said membrane seat mainly faces a direction parallel to said valve axis X. With “mainly faces a direction parallel to said valve axis” is meant herein that a normal to an outer surface of said membrane seat, when divided into one component parallel to said valve axis and one component perpendicular to said valve axis, the component parallel to said valve axis is greater than the component perpendicular to said valve axis.

Optionally, said membrane seat may be generally perpendicular to said valve axis X, i.e. a normal to the membrane seat extends generally parallel to said valve axis X. Optionally, the valve assembly is configured such that a fluid pressure of said pressurised fluid is adapted to be controlled so as to be less than a pressure of said pressurized media in said media chamber portion.

Optionally, said sealing portion of said membrane is located on said second side of said membrane.

Optionally, said seal between said valve stem and said media chamber portion at said fixed location in relation to said media chamber portion provided by said sealing portion of said membrane constitutes the only contact between the valve member and the valve body during said movement of the valve member between the open and closed position. Such an arrangement contributes to high durability for the valve as the friction between moving parts of the valve during operation of the valve may be significantly reduced.

Optionally, the valve assembly comprises a membrane member comprising the resilient membrane and a longitudinally extending portion. The longitudinally extending portion may extend generally along the valve stem. The longitudinally extending portion may be a tubular portion, extending generally along the valve axis and through which the valve stem may extend, and a membrane portion extending radially from said tubular portion and forming the resilient membrane.

Optionally, said membrane divides said valve compartment into said media chamber portion and a valve control portion. The valve control portion may be configured for receiving said pressurised fluid for applying a fluid pressure to said second side of the membrane.

Optionally, the valve control portion is configured for receiving a pressurised fluid for applying a fluid pressure to at least a pressure receiving portion of the second side of said membrane.

When the sealing portion of the membrane is located on the second side of said membrane, it will be understood that the pressure receiving portion of the second side of said membrane may be different than the sealing portion of the second side of said membrane. The sealing portion may advantageously be located radially externally of the pressure receiving portion. Optionally, the valve assembly further comprises a draining passage being in fluid communication with the valve control portion, the draining passage being configured to drain fluid from the valve control portion, upon the pressure in the valve control portion exceeding the pressure in the media chamber portion.

Optionally, the draining passage has an opening, the opening being directed towards said fixed location, i.e. the membrane seat, such that, upon the pressure in the valve control portion being lower than the pressure in the media chamber portion, the opening of the draining passage is sealed by said sealing portion; and, upon the pressure in the valve control portion exceeding the pressure in the media chamber portion, the opening of the draining passage is open to receive fluid from the valve control portion.

Optionally, the valve member is extending centrally through the valve control portion, so as to form a circumferential space between an inner wall of the valve control portion and the valve member.

Optionally, the circumferential space defines a minimum radial distance between the valve control portion inner wall and the valve member, the minimum radial distance being less than 50 microns, preferably less than 40 microns, most preferred less than 10 microns. Optionally, the minimum radial distance may be at least 1 micron.

Optionally, the valve assembly comprises a collection chamber in fluid communication with the valve control portion, preferably via the circumferential space, and the collection chamber being configured for collecting leakage from the valve control portion.

Optionally, the valve assembly comprises an air duct in fluid communication with the collection chamber, the air duct being adapted for applying an air flow to the collection chamber.

Optionally, the valve member comprises a valve closure and the valve assembly comprises a valve seat surrounding the media outlet of the media chamber portion, the valve closure and valve seat being configured to contact for closing the media outlet when the valve member is in the closed position. Optionally, the valve closure comprises a spherical valve ball.

Optionally, the valve member comprises a pressure transfer surface adapted to be operatively connected to an actuator for controlling the movement of the valve member, the pressure transfer surface preferably having a surface area transverse the valve axis X being at least 2 times, preferably at least 4 times most preferably at least 6 times greater than a surface area transverse the valve axis of the valve closure.

As such, in a variant of the valve assembly, there is provided a valve assembly for jetting of a viscous media in a media jetting device for controlled media jetting in manufacturing of three-dimensional products, such as in a 3D manufacturing device for manufacturing of 3D product by additive manufacturing, the valve assembly comprising a valve body comprising a valve compartment, the valve compartment having a media inlet for receiving pressurised viscous media, and a media outlet for ejection of the viscous media; and a valve member, arranged in the valve compartment, and being configured to be movable along a valve axis in a closing direction to a closed position in which the valve member is in a position closing the media outlet, and in an opening direction to an open position in which the valve member is in a position removed from the media outlet, allowing the pressurised media to be ejected through the media outlet.

The valve member comprises a valve stem, preferably extending generally along said valve axis X, and a resilient membrane, said resilient membrane being fixedly connected to said valve stem, and forming a membrane disc surface extending radially from and circumferentially around said valve stem and facing a direction parallel to said valve axis (X). Said valve compartment comprises a membrane seat, and at least a sealing portion of said membrane disc surface being arranged to seal towards said membrane seat during said movement of said valve member between said open position and said closed position, such that said valve compartment is divided by said membrane into a media chamber portion comprising said media inlet and outlet, and a valve control portion, said valve control portion being configured for receiving a pressurised fluid for applying a fluid pressure to said membrane. The variant of a valve assembly as set out in the immediate above may be combined with one or more of the features as set out in the above, in any combinations. The present disclosure is to encompass any such variants and combinations of features.

In a second aspect, the object is achieved by an array comprising at least two valve assemblies, preferably comprising at least 32 valve assemblies, most preferred comprising 32 to 128 valve assemblies, the valve assemblies being as described generally or in accordance with any one of the options as set out in the above. It may be preferred that the number of individual valves in the array is a number which is a multiple of 8. Optionally, an array may comprise up to 1000 valve assemblies, and for example 256 to 512 valve assemblies.

In a third aspect, the object is achieved by a 3D printing device for manufacturing of one or more 3D products by additive manufacturing using a layer-by-layer technique, comprising at least one valve assembly being as described generally or in accordance with any one of the options as set out in the above, and/or comprising an array as described in the above.

In a fourth aspect, the object is achieved by a 3D printing device for manufacturing of one or more 3D products by additive manufacturing using a layer-by-layer technique, comprising at least one valve assembly being as described generally or in accordance with any one of the options as set out in the above, and/or comprising an array as described in the above.

Optionally, the 3D printing device may comprise a control unit configured for controlling the fluid pressure of said pressurised fluid to said second side of said membrane (210) and/or controlling the media pressure in the media chamber portion of the valve assembly. Optionally, controlling the fluid pressure of said pressurised fluid involves controlling the fluid pressure in said valve control portion.

Optionally, the 3D printing device may comprise an actuator for controlling the movement of the valve member, preferably the actuator is an air pressure actuator. Optionally, the 3D printing device may comprise a control unit configured for controlling the actuator for controlling the movement of the valve member.

Optionally, the 3D printing device may comprise a control unit configured for controlling the fluid pressure of said pressurised fluid to said second side of said membrane (210) and/or controlling the media pressure in the media chamber portion of the valve assembly, and controlling the movement of the valve member. Optionally, controlling the fluid pressure of said pressurised fluid involves controlling the fluid pressure in said valve control portion.

Optionally, the 3D printing device may comprise a powder material supply for supplying powder material to the 3D printing device.

Optionally, the 3D printing device may be configured to form a 3D product by the powder material and the ejected media.

As an alternative to the third and fourth aspects mentioned in the above, there may be provided a media jetting device for media jetting in manufacturing of three-dimensional products in general. One example is the 3D printing device mentioned in the above. Another example may be a media jetting device for jetting an adhesive, such as a wood adhesive. A particular example may be a media jetting device for media jetting in wood manufacturing.

In a fifth aspect, the object is achieved by a method for controlling at least one valve assembly as described generally in the above, or in accordance with any of the options, the method comprising: supplying a pressurised fluid to said second side of said membrane so as to achieve a fluid pressure towards said second side of said membrane, and supplying a pressurised media to the media chamber portion so as to achieve a media pressure towards said first side of said membrane, and comprising controlling the fluid pressure towards the second side of the membrane in relation to the media pressure in the media chamber portion.

Optionally, the method comprises controlling the fluid pressure towards said second side of said membrane so as to be less than the media pressure in the media chamber portion. Optionally, the method comprises controlling the fluid pressure towards said second side of the membrane in relation to the media pressure in the media chamber portion.

Optionally, the method may comprise continuously controlling the fluid pressure towards said second side of the membrane in relation to the pressure of the pressurized media.

Throughout the above, controlling the fluid pressure towards said second side of the membrane may involve controlling the fluid pressure in the valve control portion.

Optionally, the method comprises controlling the movement of the valve member between the open position and the closed position by means of an actuator operatively connected to the valve member, preferably the actuator is an air pressure actuator supplying air pressure for controlling the movement of the valve member.

Optionally, when the valve assembly 1 comprises an air duct as described in the above, the method may comprise controlling an air flow to the air duct, wherein the air flow preferably provides a pressure of 100 to 200 mbar.

Optionally, the pressurised viscous media may be pressurised to 10 to 400 bar, preferably 10 to 200 bar.

Optionally, the pressure of the control fluid differs from the pressure of the pressurized viscous media by less than 10 bar, preferably less than 5 bar, most preferred less than 3 bar. Optionally, the difference may be greater than 0.1 bar.

Optionally, the pressurised viscous media is a binding agent. The binding agent may be a solvent-based or water-based adhesive, a thermoplastic adhesive or a two-component adhesive, such as acrylate, epoxy or polyester based adhesives.

Optionally, the pressurized viscous media has a viscosity greater than 50 mPas, preferably 50 to 10000 mPas.

“Viscosity” as referred to herein, is to be dynamic viscosity as given in mPas at 20 °C. In a sixth aspect, the object is achieved by the use of a valve assembly as described generally in the above, or as described in accordance with any of the options, or by the use of an array comprising at least two such valve assemblies, for ejection of a viscous media, wherein preferably the viscous media has a viscosity greater than 50 mPas, preferably 50 to 10000 mPas. Optionally, the viscous media is a binding agent.

As set out herein, the binding agent may be a water-based adhesive, a thermoplastic adhesive or a two-component adhesive, such as acrylate, epoxy or polyester based adhesives. For some applications, it may be desirable to use a two-component binding agent.

One problem which may be encountered with two-component binding agents is that they start consolidating or curing as soon as the two components are mixed. In some applications, the components may be mixed before being jetted onto the matrix material, which means that the available time for binder application is limited by the curing time for the binder. This also means that the binding agent may consolidate or cure inside the valves as disclosed herein, making the valves non-functional. Hence, it is highly desirable that the valves may be cleaned and regenerated for reuse in a simple and cost efficient manner even if they have been clogged by binding agent.

Further options and advantages are disclosed in the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Below follows a more detailed description of example valve assemblies, methods and 3D devices with reference to the appended drawings, wherein:

Fig. 1 is a schematic cross-sectional view of a variant of a valve assembly 1 as disclosed herein;

Fig. 2 is a schematic cross-sectional view of the valve assembly 1 of Fig. 1, taken perpendicular to the view in Fig. 1 ;

Fig. 3 is an enlarged portion of Fig. 1;

Fig. 4 is a cross-sectional view of the valve member 20 as depicted in Figs. 1-3;

Fig. 5 is a schematic illustration of an array 1000 of valve assemblies 1; and Fig. 6 is a schematic illustration of a 3D printing device.

Like reference numerals refer to the same features in the Figures.

DETAILED DESCRIPTION

Figs 1 to 4 illustrate an example of a valve assembly 1 as proposed in this application.

The exemplified valve assembly 1 is configured for ejection of a viscous media in a 3D printing device for manufacturing of one or more 3D products by additive manufacturing. As set out in the introduction of the application, the dimensions of the valve assembly 1 may therefore be selected to be suitable for 3D manufacturing. For example, an outermost width of the valve assembly may be less than 10 mm.

The valve assembly 1 comprises a valve body 10 and a valve member 20. The valve body 10 defines a valve compartment 100 having a media inlet 101 for receiving pressurised viscous media and a media outlet 102 for ejection of the viscous media from the valve assembly 1.

The valve body 10 may be manufactured from a wear resistant and unflexible material, such as a metal material.

The valve member 20 is arranged in the valve compartment 100 and configured to be movable along a valve axis X. The valve member 20 is movable in a closing direction to a closed position, in which the valve member 20 is in a position closing the media outlet 102, and in an open direction to an open position in which the valve member is in a position removed from the media outlet 102, allowing the pressurised media to be ejected through the media outlet 102.

The valve member 20 comprises a valve stem 200, extending generally along the valve axis X, and a resilient membrane 210.

With “resilient” is meant having the ability to deform under a deforming force or pressure, and to recover an original shape quickly when the deforming force or pressure is removed. The resilient membrane 210 may advantageously be formed by a resilient material, such as rubber. The illustrated valve assembly 1 is especially suitable for ejection of corrosive or highly abrasive media, which furthermore has a high viscosity.

The resilient membrane 210 is fixedly connected to the valve stem 200, and forms a membrane disc surface 211 extending circumferentially around the valve stem 200 and mainly facing a direction parallel to the valve axis X. Optionally, the membrane disc surface may extend generally perpendicular to the valve axis X.

The valve compartment 100 comprises a membrane seat 110, i.e. the valve body 10 comprises an inner wall forming the wall compartment 100, and the membrane seat 110 is formed by a part of said inner wall.

A sealing portion 213 of the membrane disc surface 211 is arranged to seal towards the membrane seat 110 during the movement of the valve member 20 between the open position and the closed position.

It is to be understood that the resilient membrane 210 is to be resilient at least in a direction along the valve axis X.

By virtue of the resilient membrane 210, continuous sealing contact is achieved between at least the sealing portion 213 of the membrane disc surface 211 and the membrane seat 110 while the valve assembly is in use for ejecting viscous media, i. e. while the valve member 20 moves between the open position and the closed position.

Accordingly, the resilient membrane 210 is arranged to divide the valve compartment 100 into a media chamber portion 120, comprising the media inlet 101 and outlet 102, and a valve control portion 130. Hence, a first side of said membrane 210 is subject to a media pressure residing in said media chamber portion 120, and the valve assembly 1 is configured for applying a pressurised fluid to a second side of said membrane 210 opposing said first side.

The media chamber portion 120 is configured to receive pressurised media via the media inlet 101, and to allow ejection of the pressurised media via the media outlet 102, when the valve member 20 is in the open position. The media chamber portion 120 is sealed towards the valve stem 200 by the resilient membrane 210. Accordingly, the resilient membrane 210 will be subject to the pressure in the media chamber portion 120, i.e. to the pressure of the pressurised media, on a first side thereof.

The portion of the valve compartment 100 on the side of the resilient membrane 120 opposite the media chamber portion 120 defines, as stated in the above, a valve control portion 130. The valve control portion 130 is configured for receiving a pressurised fluid for applying a fluid pressure to the resilient membrane 210, i.e. to a second side of the resilient membrane 210 opposing the first side.

When the valve control portion 130 receives the pressurised fluid for applying a fluid pressure to the resilient membrane 210, it is understood that the pressurised fluid in the valve control portion 130 will act on the second side of the resilient membrane 210, whereas the pressurised media in the media chamber portion 120 will act on the first side of the resilient membrane 210.

Accordingly, the pressure of the pressurised fluid in the valve control portion 130 may be selected in relation to the pressure of the pressurised media in the media chamber portion 120 so as to delimit the resulting pressure difference over the resilient membrane 210.

To achieve the above-mentioned sealing contact between the membrane disc surface 211 and the membrane seat 110, it is desired that there is indeed a difference between the pressure in the valve control portion 130 and the pressure in the media chamber portion 120. The difference will be effective for urging the resilient membrane 210 towards the membrane seat 110.

However, if the difference between the pressure in the valve control portion 130 and the pressure in the media chamber portion 120 is relatively large, then there is a risk that the resilient membrane 210 will break, or that it will be pushed into the valve control portion 130, losing the sealing contact with the membrane seat 110, and /or becoming subject to wear and risk breaking. With the valve assembly 1 as proposed in the above, the fluid pressure in the valve control portion 130 may however be selected in relation to the pressure of the pressurised media in the media chamber portion 120 so as to control the resulting pressure difference over the resilient membrane 210.

In particular, this enables the proposed valve assembly to be used for ejection of media with very high viscosity, requiring a media pressure in the media chamber portion in the range 15 to 60 bar, perhaps in the range 15 to 200 bar or even 15 to 400 bar.

The pressure difference over the resilient membrane 210 may for example be held at less than 10 bar, preferably less than 5 bar.

The pressurised fluid to be received in the valve control portion 130 may be any suitable hydraulic fluid. To this end, the control fluid may be selected to be a fluid which is in liquid form at the pressures relevant for the desired application. Advantageously, the control fluid may comprise a lubricant fluid, diminishing wear of the valve assembly 1. For example, the control fluid may be a vegetable hydraulic fluid.

Optionally, and as in the illustrated valve assembly 1, the membrane disc surface 211 (out of which a portion is in contact with the membrane seat 110) faces towards the opening direction. In this case, the membrane seat 110 would generally face towards the closing direction of the valve assembly 1.

Advantageously, the fluid pressure in the valve control portion 130 is adapted to be controlled to be less than the pressure of the pressurised media in the media chamber portion 120. Accordingly, the membrane disc surface 211 as in the illustrated embodiment will be brought into sealing contact with the membrane seat 110 with the aid of the pressure difference over the membrane 210.

Advantageously, the fluid pressure in the valve control portion 130 is adapted to be controlled in relation to the media pressure in the media chamber portion 120.

Accordingly, the sealing contact between at least a sealing portion of the membrane disc surface 211 and the membrane seat 110 during use of the valve assembly 1 is to be ensured. Turning to the valve control portion 130, the valve body 100 may comprise at least one control fluid inlet 131. In the illustrated variant, two control fluid inlets 131 are arranged.

Turning now to the construction of the valve assembly 1 for enabling opening and closing so as to allow or hinder ejection of pressurised media via the media outlet 102, an advantageous variant as illustrated in the drawings will now be described.

The valve member 20 comprises a valve closure 230 and the valve body 10 comprises a valve seat 170 surrounding the media outlet 102. The valve closure 230 and valve seat 170 are configured to contact for closing the media outlet 102 when the valve member 20 is in the closed position.

Optionally, and as in the illustrated variant, the valve closure 230 comprises a spherical valve ball 230. The valve closure, e.g. the valve ball, may advantageously be made by a material having a hardness being greater than 7, e.g. about 8 (Mohs scale hardness). For example, the valve closure 230 may be made of silicon nitride (Si3N4) or cubic zirconia.

The seat 170 may, as in the illustrated embodiment be formed by a seat part 173 separate from the main valve body 10. This enables the seat 173 to be manufactured by a material having a hardness being greater than 7 (Mohs hardness scale), i.e. corresponding to the hardness of the valve closure 230, while the valve body 10 may be manufactured by another material. For example, the valve seat part 173 may be made by zircon.

The valve seat part 173 may comprise an outlet passage 171 which forms the media outlet 102 of the valve assembly 1. For example, the valve seat 170 may be a generally circular cylindrical portion through which the outlet passage 171 extends.

To enable ejection of media such as corrosive/high friction media as mentioned in the introduction of the application, the materials of the valve closure 230 and seat 170 may generally be selected from materials being resistant to wear by friction and to corrosion from chemicals present in the media. In the illustrated variant, the valve seat 170 is attached the valve body 1 by a seat seal 172. The seat seal 172 may for example be in the form of an o-ring.

The valve member 20 is configured to be operatively connected to an actuator 3 for controlling the movement of the valve member 20 for opening and closing the media outlet of the valve assembly 1. (See Fig. 6.)

The actuator 3 may be any actuator suitable for performing the necessary control with high speed and accuracy as explained in the introduction to the application.

Preferably, the actuator 3 may be an air pressure actuator, configured to control the valve member 20 by generating air pressure to control the opening and closing of the valve arrangement 1.

The valve member 20 may comprise a pressure transfer surface 220 adapted to be operatively connected to an actuator 3. The pressure transfer surface 220 is adapted to receive a pressure from the actuator 3, such as an air pressure in the case of an air pressure actuator, and to transfer it to the valve closure 230 via the valve member 20.

To enable the valve closure 230 to be moved between the open and closed positions of the valve assembly 1 , the pressure from the valve stem 200 at the valve closure 230 should be adapted to the pressure in the media chamber portion 120, i.e. to the pressure of the pressurized media. As mentioned in the above, for ejection of high viscosity media, the media is pressurized to relatively high pressures, e.g. to pressures above 10 bar, preferably 10 to 200 bar or even 10 to 400 bar.

Advantageously, the pressure transfer surface 220 has a pressure receiving area perpendicular to the valve stem 200 being greater than an area of the valve closure 230 perpendicular to the valve stem 200. Accordingly, the pressure exerted by the actuator to the pressure transfer surface 220 is increased when reaching the valve stem 200 with a factor corresponding to the difference in areas. By this arrangement, as an example, an air pressure actuator giving 3 bar of air pressure to the pressure transfer surface 220 may result in a pressure at the valve closure 230 of 60 bar.

The valve stem 200 may comprise several parts. For example, and as in the illustrated variant, the valve stem 200 may comprise a valve needle 240. A first end of the valve needle 240 may be adapted to carry the valve closure 230.

When, as in the illustrated variant, the valve closure 230 is in the form of a spherical valve ball 230, the first end of the valve needle 240 may form a valve closure compartment for holding the spherical valve ball 230. The spherical valve ball 230 is fixedly arranged in the valve closure compartment.

The resilient membrane 210 may, as exemplified in the illustrated variant, be fixed to the valve needle 240. To this end, there may be provided a membrane member 212, comprising a tubular portion, extending generally along the valve axis and through which the valve needle 240 may extend, and a membrane portion extending radially and forming the resilient membrane 210. As such, the tubular portion of the membrane member 212 forms part of the valve stem 200, whereas the membrane portion forms the resilient membrane 210.

Generally, in different variants of the valve assemblies as described herein, a membrane member forming the resilient membrane and a longitudinally extending portion forming part of the valve stem or surrounding the valve stem may be advantageous for pressure distribution adjacent the resilient membrane. The resilient membrane and the longitudinally extending portion will generally be subject to pressure, e.g. the pressure in the media chamber. This pressure may contribute to sealing between the membrane member and the valve stem/valve needle.

A second end of the valve needle 240 may be connected to an actuator transfer member 250, adapted to be connected to an actuator 3. The actuator transfer member 250 may comprise the pressure transfer surface 220 for transferring pressure received from the actuator 3 to the valve stem 200. The actuator transfer member 250 may, as exemplified in the illustrated variant, comprise an elongate pin portion extending along the valve axis, and a pressure transfer surface portion 220 forming the pressure transfer surface 220.

The elongate pin portion may comprise a bore in which the second end of the valve needle 240 is arranged, for example by threading. As such, the elongate pin portion of the actuator transfer member 250 forms part of the valve stem 200. In variants using a membrane member 212 and an actuator transfer member 250 both being attached to a valve needle 240, the membrane member 212 and the actuator transfer member 250 may be arranged to the valve needle 240 in contact with each other, as exemplified in the illustrated variant.

Advantageously, the valve member 20 and the valve body 10 are arranged such that the sealing contact between the portion of the membrane disc surface 211 being arranged to seal towards the membrane seat 110 during the movement of the valve member 20 between the open position and the closed position constitutes the only contact between the valve member 20 and the valve body 10 during movement of the valve member 20 between the open and closed position. With the only contact between the valve member 20 and the valve body 10 being via the resilient membrane 211, friction and wear between parts may be reduced.

The valve member 20 may, as for example in the illustrated variant, extend centrally through the valve control portion 130, so as to form a circumferential space 150 between an inner wall of the valve control portion 130 and the valve member 20. The pressurised fluid in the circumferential space 150 will exert a circumferential pressure to the valve member 20, acting so as to maintain the valve member 20 centrally in the valve control portion 30.

Accordingly, the valve member 20 may be held correctly positioned in the valve body 10 while comprising no further devices extending between the valve member 20 and the valve body 10 but the resilient membrane 210.

As seen in the example variant illustrated in Figs 1-4, the circumferential space 150 is open to the exterior of the valve body 10. An open gap 151 is formed between the valve body 10 and the valve member 20 towards the exterior of the valve body 10.

The circumferential space 150 may define a minimum radial distance between the valve control portion inner wall and the valve member, the minimum radial distance being less than 50 microns, preferably less than 40 microns. The minimum radial distance between the valve control inner wall and the valve member may be provided along a selected length being a portion of complete length along which the valve control inner wall and the valve member run adjacent to each other. Said selected length may be less than the complete length, for example less than half the length.

The open gap 151 may define a radial distance between the valve control portion inner wall and the valve member 20 being less than 50 microns, preferably less than 40 microns. Most preferred, as in the illustrated variant, the radial distance may be less than 30 microns, e.g. in the range 20-30 microns.

The open gap 151 having relatively small dimensions, together with the relatively high pressure of the control fluid, acts so as to create a hydrostatic boundary between the valve member 20 and the valve control portion inner wall, which centres the valve member in the valve control portion with almost no friction between the parts.

The open gap 151 between the valve member 20 and the valve body 1 may cause some control fluid to leak out from the valve control portion 130. To take care of this leakage, the valve assembly 1 may comprise a collection chamber 160 in fluid communication with the valve control portion 130, preferably via the circumferential space 150. The collection chamber 160 may be configured for collecting leakage of control fluid from the valve control portion 130.

To remove collected leakage of control fluid from the collection chamber 160, the valve assembly may comprise an air duct 165 in fluid communication with the collection chamber 160, the air duct being adapted for applying a low pressure air flow to the collection chamber.

Accordingly, leaked control fluid may be removed from the collection chamber 160 such that the risk of the collected fluid having an impact on the movement of the valve member 20 is reduced.

As seen for example in the illustrated variant, a cover element 180 may be arranged so as to cover over the valve body 10 and the valve member 20. The cover element 180 may be arranged so as to cover the open gap 151 , thereby isolating the control fluid in the valve assembly 1.

The cover element 180 may be arranged to extend over the entire valve member 20. In this case, pressure from the actuator 3 may be applied to the valve member 20, in particular to the pressure transfer surface 220, via the cover element 180.

The cover element 180 may be in the form of an elastic membrane, allowing movement of the valve member 20 and transfer of e.g. air pressure from an actuator 3 to the valve member 20, e.g. to the pressure transfer surface 220.

As explained in the above, the pressure difference over the membrane is advantageously controlled during the use of the valve assembly 1, for example the pressure difference over the membrane may be continuously controlled. However, should the pressure of the pressurised media in the media chamber portion 120 momentarily decrease, there is a risk that such a control is not able to immediately decrease the fluid pressure in the valve control portion 130. Hence, in this case there is a risk that the membrane 210 is pushed into the media chamber portion 120 and breaks.

To alleviate this risk, the valve body 10 may optionally, and as in the illustrated variant comprise a draining passage 140 being in fluid communication with the valve control portion 130, the draining passage 140 being configured to drain control fluid from the valve control portion 130 upon the pressure in the valve control portion 130 exceeding the pressure in the media chamber portion 120.

The draining passage 140 may have an opening 141 towards the membrane seat 110. Accordingly, when the pressure in the valve control portion 130 is lower than the pressure in the media chamber portion 120, as during normal use, the opening 141 of the draining passage 140 is closed by the membrane disc surface 211 being in sealing contact with the membrane seat 110. However, upon the pressure in the valve control portion 130 being greater than the pressure in the media chamber portion 120, the membrane 210 moves from sealing contact with the membrane seat 110, resulting in that the opening 141 of the draining passage 140 is open. The pressurised fluid in the valve control portion 130 may now enter the fluid draining passage 140 via the opening 141. By virtue of control fluid being drained away via the fluid draining passage 140, the pressure in the valve control portion 130 will decrease, and the membrane 210 will not risk being pushed further into the media chamber portion 120. In other words, when the membrane 210 moves slightly into the media chamber portion 120, this results in the draining passage 140 being opened, and the pressure in the valve control portion 130 being reduced. Accordingly, the membrane 210 will be hindered from continuing to move further into the media chamber portion 120.

To ensure that the draining passage 140 may alleviate the pressure in the valve control portion 130, the total flow area of the draining passage 140 (or passages) may be greater than the total flow area of the control fluid inlets 131 to the valve control portion 130. To this end, a plurality of draining passages 140 may be provided, for example 2 to 12 draining passages 140.

Optionally and as in the illustrated variant, the draining passages 140 open into a groove formed in the membrane seat 110, and the membrane 210 is provided with a rib corresponding to said groove.

Optionally and as in the illustrated variant, the draining passage 140 may be connected to a draining channel. In the illustrated variant, each of the two draining passages 140 is connected to a corresponding draining channel.

The valve body 10 may advantageously be made out of at least two separable parts 11,

12, being separable for regeneration of the valve assembly. The two separable parts 11,

12 may be configured so as to be separable to enable replacement of pieces of the valve assembly 1 subject to wear. In particular, the two separable parts 11, 12 may be configured so as to be separable to enable replacement of the resilient membrane 210, the seat part 173, the valve closure 230 and/or the seat seal 172.

Optionally, and as in the illustrated embodiment, the two separable parts may be a control body part 11 and a media body part 12. The control body part 11 and the media body part 12 may be separable at a level of the resilient membrane 210.

Hence, for regeneration of the valve assembly 1 , the control body part 11 and the media body part 12 may be separated, and the media body part 12 may be subject to pyrolytic cleaning to remove residual media, such as cured binder residues, from the media body part. The media body part 12 may as an alternative or a complement be subject to ultrasonic cleaning. The resilient membrane 210 may be replaced with a new resilient membrane 210, and the seat seal 172 may also be replaced.

The valves as disclosed herein are preferably made so as to be easy and economically recoverable and prepared for reuse. To this end, the materials for valve parts such as the valve body 10 and parts of the valve member 20 may be selected to withstand pyrolytic cleaning, i.e. high temperature cleaning which serves to remove any binder residue in the valve as well as parts subject to wear, such as the resilient membrane 210 and/or the seat seal 172. Suitable materials for the reusable parts may be metallic or ceramic material capable of enduring temperatures suitable for pyrolytic cleaning. The valves as disclosed herein may be regenerated after a predetermined number of working cycles or after failure e.g. caused by binder clogging.

Optionally, and as in the illustrated embodiment, the valve body 10 (the control body part 11) forms an inner circumferential wall delimiting the circumferential space 150 formed between the valve body 10 and the valve member 20. To this end, the valve body 10 may be provided with a through bore, which may be adapted to the size of the valve stem 200 with high precision.

Optionally, and as in the illustrated embodiment, the valve body 10 forms an end wall 191 facing the opening direction of the valve assembly 1 , which opposes a portion of the resilient membrane 210, forming a control fluid gap 152 between the end wall 191 of the valve body 10 and the pressure receiving portion 214 of the resilient membrane 210. Control fluid in the control fluid gap 152 will hence provide the desired fluid pressure to the resilient membrane 210.

The control fluid inlets 131 may be arranged to supply control fluid to the control fluid gap 152. The valve control portion 130 may comprise the control fluid gap 152 and the circumferential space 150. Control fluid provided via the control fluid inlets 131 may flow to the control fluid gap 152 to exert the fluid pressure, further to the circumferential space 150 where it may act to keep the valve stem 200 centered, and residual control fluid may leak out at the open gap 151, where it may be collected in the collecting chamber 160 and removed by air duct 165. A valve assembly as described herein may be adapted for jetting viscous media having different temperatures by selection of appropriate materials for the different parts of the valve assembly. For example, if it is desired to jet a melted plastic material the membrane may be selected from resilient materials capable of withstanding relatively high temperatures.

Fig. 5 illustrates schematically an array 1000 comprising at least two schematically illustrated valve assemblies 1. As indicted by the dotted line in Fig. 5, the array 1000 may comprise any selected number of valve assemblies 1. It is preferred however to use between 16 and 128 valve assemblies.

Fig. 6 illustrates schematically a variant of a 3D printing device comprising an array 1000 comprising at least two valve assemblies 1. The 3D printing device may, as in the illustrated variant, comprise a control unit 4. The control unit 4 may be configured for controlling the fluid pressure in the valve control portion 130 of the valve assemblies 1 and/or controlling the media pressure in the media chamber portion 120 of the valve assemblies 1. The 3D printing device may comprise actuators 3 for individually controlling the opening and closing of the valve assemblies 1.

The control unit 4 may advantageously be configured for controlling also the actuator 3. The 3D printing device may comprise further members and systems as known in the art of 3D printing. In particular, the 3D printing device may be configured for binder jetting manufacturing methods. The 3D printing device may for example comprise a supply system for supplying material powder to be bonded by a binder agent being the viscous media ejected by the valve assemblies 1.

As may be understood from the description of the valve assembly 1 in the above, a method for controlling at least one valve assembly 1 may comprise: supplying a pressurised fluid to the valve control portion 130 so as to achieve a fluid pressure in the valve control portion 130, and supplying a pressurised media to the media chamber portion 120. The method may further comprise controlling the fluid pressure in the valve control portion 130 in relation to the pressure of the pressurised media in the media chamber portion 120. Optionally, the method may comprise controlling the fluid pressure in the valve control portion 130 so as to be less than the pressure of the pressurised media in the media chamber portion 120.

Optionally, the method may comprise controlling the fluid pressure in the valve control portion 130 in relation to the pressure of the pressurised media in the media chamber portion 120.

Optionally, the method may comprise controlling the movement of the valve member 20 between the open position and the closed position by means of an actuator 3 operatively connected to the valve member 20, preferably the actuator 3 is an air pressure actuator supplying air pressure for controlling the movement of the valve member 20.

Optionally, when the valve assembly comprises an air duct 165, the method may comprise controlling an air flow to the air duct 165, wherein the air flow preferably provides a pressure of 50 - 500 mbar.

Optionally, the pressurised viscous media is pressurised to 10 to 400 bars, preferably 10 to 60 bars.

Optionally, the pressure of the control fluid differs from the pressure of the pressurised viscous media by less than 10 bar, preferably less than 5 bar, most preferred less than 3 bar. Optionally, the difference may be greater than 0.1 bar.

Optionally, the pressurised viscous media is a binding agent. The binding agent may be a solvent-based or water-based adhesive, a thermoplastic adhesive or a two-component adhesive, such as acrylate, epoxy or polyester based adhesives.

In view of the above description, a use of at least one valve assembly 1 or of an array 1000 for ejection of a viscous media is also described. Preferably the viscous media has a viscosity greater than 50 mPas, preferably 50 to 10 000 mPas.

The viscous media may be a binding agent, such as a solvent-based or water-based adhesive, a thermoplastic adhesive or a two-component adhesive. For example, the viscous media may be a two-component adhesive, such as acrylate, epoxy or polyester based adhesives. Numerous variants and options of the devices and methods disclosed herein will be conceivable by the person skilled in the art. For example, in the illustrated variants the resilient membrane is generally circular, and extends radially from a circumferentially around the valve stem with the valve stem in the centre of the circular membrane. However, other shapes of the resilient membrane are possible, and the valve stem need not necessarily be positioned in the centre of the resilient membrane. Further, in the variants described in the above, the actuator is exemplified by an air pressure actuator. However, other actuators may be used, for example a piezo actuator.